The opposite of swag. Whereas swag is usually associated as "cool" "chill" "confident", etc., reverse swag is where you do something that is either:
1. socially embarrassing that is not in line with the swag philosophy.
2. You are on a swag roll, hitting on a member of the opposite sex, yet get rejected.
3. Doing something you perceive as cool but is not swag at all.

1-3 intertwine sometimes.

It can be used as a hash tag (#reverseswag)
The term was coined by _zer0 on a stickam chat.

You're a guy and wearing your most ballin' outfit and you go to the club to pick up chicks. You find a hot Asian girl. You go up to her and say, "Girl, what's your favorite Pokemon?"
#reverse swag

You're walking down the street, everyone sees how ballin' you are. You trip and fall on your face.
Reverse Swag.